Item Name: Brass With Chuck Key Clamping Range Drill Chuck Micro Motor 0.3-4mm Taper. JT0 taper the biggest end of diameter: 6.350mmFeatures:High precision screw thread and tapered hole.Work with 0.3mm-4mm ( 0.01" - 0.16") Drill,The maximum clamping 4.2mm.Compatible with impact dril and different power electric drill.Connection size: JT0 (inner hole diameter is 6 mm)Taper: 2 degrees 49 minutes 24.7 secondsJT0 taper The smallest end of diameter: 5.800mmOuter diameter: 21.5mmStrong impact resistance.Package list:1 pcs Drill Chuck 1 pcs T spanner1 pcs L spanner1 pcs 3.17mm connector note: Does not include motor *Please make